Motor fuel composition



United States Patent 3,223,495 MOTOR FUEL COMPOSITION Louis N. Calvino, Scotch Plains, and Monroe W. Munsell, Berkeley Heights, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Sept. 11, 1961, Ser. No. 137,037 8 Claims. (Cl. 4471) The present invention relates to improved motor fuels for use in internal combustion engines and more particularly relates to gasolines having incorporated therein a certain combination of low molecular weight polymeric dispersantdctergent additive agents which markedly reduce the formation of deposits, sludge and varnish in gasoline engines.

Despite the relatively high efficiency of modern gasoline engines, complete combustion of the fuel introduced into the combustion chambers of such engines seldom, if ever, occurs. Studies have shown that certain polynuclear aromatic compounds and other relatively high boiling materials present in gasoliues are only partially burned and that the exhaust gases formed in the combustion chambers of gasoline engines contain trace amounts of hydrocarbons. Apparently these hydrocarbons undergo complex cracking, polymerization and oxidation reactions to form carbonaceous deposits which adhere to the upper part of the cylinder head, the valves, the piston tops and other surfaces in the engine with which the hot gases come into contact. When the lubricating oil subsequently comes into contact with hot metal surfaces, these materials react to form insoluble products. It has been shown that practically all the sludge in crankcase oils and most of the varnish on piston skirts, connecting rods, crankshafts and similar engine 'parts are thus due to constituents which were originally present in the gasoline.

Deposits, sludge and varnish formed in this manner seriously affect the operation of a gasoline engine. The role which combustion chamber deposits play in promoting surface ignition, spark plug fouling, rumble, octane requirement increase and similar combustion difiiculties is generally well known. Less familiar but equally serious is the tendency of these foreign materials to cause malfunctioning of the engine lubricating system, to accelerate the rate at which the wear of engine parts occurs, to increase engine oil consumption, and to produce improper valve and piston ring operation, leading to serious losses in engine power Because of these adverse effects, efforts have been made to improve the combustion in gasoline engines and decrease the formation of deposits, sludge and varnish by a variety of methods, including the use of solvent oils and other additives in the gasoline.

In the past, various detergent and dispersant type additives have been employed in the nonvolatile, high boiling, crankcase mineral lubricating oil to aid in suspending these insoluble products, and to effect cleanliness of those engine area-s where the lubricating oil came into direct liquid contact. The employment of high molecular weight polymeric additives in volatile fuels like gasoline has been generally avoided since the nonvolatile, high molecular weight and polymeric nature of these additives tends to have a detrimental effect on upper engine cleanliness, such as in increasing the level of the intake valve underside deposits. Additionally, the effective functioning of these additives after high temperature combustion,

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together with the volatile fuel in a combustion chamber, was in considerable doubt.

It has now been discovered that a combination of a particular low molecular weight, ashless, oil soluble, dispersant type polymeric additive and a low molecular weight, ashless, oil soluble, detergent additive, both having an average molecular weight of less than 20,000, effectively complement one another to provide a significant reduction in overall engine cleanliness when incorporated in a volatile motor fuel at very low concentration levels. This combination reduces and inhibits the formation or deposition of varnish, sludge, and gum in an internal combustion engine. Further, this unique and particular combination of additives functions to maintain a high cleanliness level in the fuel lines and carburetor area. Moreover, this combination allows a reduction in deposit formation even in those areas not directly contacted with liquid gasoline fuel, such as the timing gear cover, the rocker arm cover, rocker arm assembly area, push rod chamber, crankcase, and crankshaft. The functioning of the polymeric combination is surprising in that it survives the combustion of the volatile fuel. A further unexpected advantage obtained by the use of the combined additives of the instantly described class is the marked reduction in engine deposit which is considerably superior to the use of each polymer when separately employed in gasoline. Thus, the applicants have discovered a unique method of directly promoting overall engine cleanliness by incorporating very small amounts of the additive combination in a volatile fuel, thereby giving marked advantages over the required incorporation of higher concentration levels in heavy mineral oils, and yielding far more beneficial results.

To obtain the beneficial results of the instant invention, the additive combination is incorporated in minor amounts sufiicient to enhance overall engine cleanliness. The quantities employed will, of course, depend in part on the fuel components, the engine, and the driving conditions encountered, but normally are employed in very small quantities in a volatile fuel at a total active concentration level of between 0.001 and 1.0 wt. percent and preferably between 0.005 and 0.20 wt. percent. The ratio of the dispersant to detergent additive may vary between 5/1 and 1/5, with a ratio of between 3/1 and 1/1 preferred. The additives may be directly incorporated in the motor fuel singly or in combination or in an oil concentrate form alone or together with other conventional fuel additives as described. Further, the polymeric additive agents may be incorporated in solvent oils or in gasolines containing minor amounts, e.g. 0.5 to 3.0 wt. percent, of such oils such as light mineral hydrocarbon gasoline solvent oils such as a naphthene or paraffin base, acid treated and neutralized distillate having SUS viscositie-s at F. of between 50 and 500 seconds.

The oil soluble, low molecular weight, ashless, dispersant polymers are those polymers which function as dispersants in lubricating oils and generally have a polyolefin backbone modified by the incorporation of carbonyl and nitrogen functions in the molecule. These polymers are particularly obtained by the reaction of a long chain, alkenyl substituted, dicarboxylic acid or anhydride with a polyamine and thus are N-substituted polyamine alkenyl dicarboxylic imides, and particularly N-substituted mono 030400 alkenyl succinimides derived from tetraethylene pentamine. The preferred additive is prepared by the reaction of a monoalkenyl succinic acid anhydride with a polyalkylene diamine to give products such as N-alkyl amino alkenyl succinirnlide like N-ethyl amino polybutene succinimide.

The preparation of these polymeric additives is generally accomplished in two successive reactions with product purification steps following either or both reactions dependent upon the desired level of product purity. The first reaction is carried out by reacting approximately a polyolefin with a dicarboxylic acid or anhydride in a ratio of acid to polyolefin of 1:10, e.g. 1:5, at temperatures of about 300 to 450 F., e.g. 375 to 450 F. When maleic anhydride is employed, this reaction can be accomplished at atmospheric pressure while other suitable 1:, 3 unsaturated dicarboxylic acids might require elevated pressures. The reaction product comprises primarily a monoalkenyl dicarboxylic anhydride which is then dissolved in an inert organic solvent such as xylene and further reacted, e.g. at 80 to 100 C., with approximately equimolar quantities of an aliphatic polyamine. The water condensate produced ,may then be azeotropically stripped with the xylene solvent and the oil soluble, monoalkenyl, dicarboxylic imide additive product recovered.

The alkenyl radical of the product is obtained by the use of an oil soluble, polyolefinic hydrocarbon derived from the polymerization of a monoolefin having from 4 to 12, e.g. 4 to 6, carbon atoms per molecule. The hydrocarbon polyolefins employed are preferably derived from monoolefins having an allylic hydrogen, and generally possess weight average molecular weights as determined by the boiling point elevation method of from about 600 to 10,000 or even higher, e.g., 20,000; suitable ranges include 600 to 3,000 or 1,000 to 2,000. The alkenyl radical should have a carbon atom chain length of more than about 50 carbon atoms, eg 50 to 300, with about 70 to 100 carbon atoms preferred, although no critical upper limitation apparently exists. The employment of shorter chain lengths such as from 4 to 30 carbon atoms is not particularly suitable for the purposes of the instant invention, since the shorter chain length fails to provide the molecule with enough oil solubility to function as a proper sludge dispersant. Shorter carbon chains, while oil soluble products, are easily occluded by the sludge and result in reduced efiiciency, especially when employed in combination with the phosphosulfurized additives of this invent-ion. The liquid hydrocarbon polybutenes comprising from 85 to 98 Wt. percent of monoolefinic polybutene are the especially preferred olefins although suitable alkenyl radicals may be obtained by polymerizing and copolymerizing olefins such as ethylene, propylene, l-butene, isobutene, isoprene and isobutylene, and the like. These olefins or polyolefins or the copolymers may be phosphosulfurized, steam blown, or neutralized, or any combination thereof as described, either prior to reaction with the ,5 unsaturated dicarboxylic acid or after the formation of the monoalkenyl acid anhydride. Neutralization with a polyamine may be accomplished at the same time as the formation of the imide or in separate steps.

The dicarboxylic acids or anhydrides hereinafter generally referred to as acidic employed as reactants include all 01,;3 unsaturated acids or anhydrides which form stable fiveor six-membered cyclic up unsaturated anhydrides at atmospheric pressure and temperature, or which isomerize or condense to form 3 unsaturated cis oriented anhydrides at the reaction temperatures employed, e.g. When heated to 200 C. Suitable acids and anhydrides include aliphatic dicarboxylic acids, e.g. butenedioic acids, such as maleic acid, maleic anhydride, and itaconic and citraconic acid, or anhydride and C to C alkyl and alkylene substituted butenedioic acids, or more broadly, any 04,18 unsaturated acid or anhydride which is an active Diels-Alder dienophile, with the preferred reactant being maleic anhydride due to economic availability and performance.

The alkenyl dicarboxylic acid anhydrides obtained from the first step of the preparation and dissolved in, for example, benzene at 25 wt. percent are then reacted with equimolar quantities of a polyamine. Suitable and nonlimited examples of polyamines include those aliphatic polyamines such as those polyalkylene polyamines, e.g. the polyalkylene diamines, and those further described in U.S. Patent 2,638,450. For the purposes of the instant invention, the preferred polyamines are the polyalkylene diamines such as the diamines having the general formula:

wherein R is a C to C alklene radical such as methylene, ethylene, propylene, butylene and the like, and x is a number from 1 to 6, e.g. 3 to 5. These diamines include the 1,2 and 1,3-propylene diamines, the ethylene diamines, methylene diamines, etc. Although polyamines in general are suitable, the ethylene diamines, such as the tetraethylene pentamine products are very effective and are especially preferred since the higher polyand diamines tend to decrease oil solubility and require a corresponding increase in the length of the hydrocarbon alkenyl group of the dicarboxylic acid to maintain the desired hydrophilic and oleophilic balance required for sludge dispersancy in a volatile fuel. Another polyamine suitable for the purposes of the invention includes dialkyl amino alkyl amines like dimethyl amino methyl amine, diethyl amino propyl amine, and the like, which give N-dialkyl amino alkyl monoalkenyl succinimides.

The low molecular weight oil soluble alkenyl dicarboxylic imide polymers are represented by the following structural formula:

wherein R comprises an alkenyl radical such as a hydrocarbon polymer or copolymer, that is, a polyolefin 0btaned from the polymerization of a C monoolefin, said polyolefin having an average molecular weight of between 600 and 3,000 and preferably is a polybutene, R is a radical selected from the group consisting of hydrogen and C to C alkyl radicals, R' is a C to C alkylene radical, preferably ethylene, and x is a number from 1 to 6, preferably 5, and R comprises a C to C radical containing substituents selected from the group consisting of hydrogen and C to C alkyl radicals, e.g. C to C and preferably is a methyl group.

Thus, the employment of these particular dispersant additives in a highly volatile fuel such as gasoline generally avoids the disadvantages of a high molecular weight polymeric additive in tending to increase deposit level in certain engine areas, while providing suflicient oi-l solubility and functional characteristics to be effective sludge dispersants and to survive the combustion chamber burning effects.

The low molecular weight detergent inhibitor additives of the invention may comprise those oil soluble, low molecular weight, e.g. to 900, metallic salts such as the alkali and alkaline earth salts of petroleum sulfonates, alkyl phenol sulfides, phenates, and the like such as calcium sulfonate, barium phenate, calcium dodecyl phenol sulfide and the like. These additives are not as effective as the preferred additives due in part to their metallic ashforming character.

The preferred low molecular weight detergent additives of the invention are those oil soluble, ashless, phosphosulfurized, hydrolyzed, neutralized polymers prepared by the reaction of a hydrocarbon with a sulfide of phosphorus.

The phosphosoulfurization agent may be P 8 P S P 8 P 8 or their mixtures, or mixtures of elemental phosphorus and sulfur or other materials. A sulfide of phosphorus, especially phosphorus pentasulfide (P 5 is preferred. Generally, in the range of about 1.0 to 50.0% by weight, based on the hydrocarbon, of phosphosulfurizing agent is used. A preferred range is about 5 to 25, e.g. to 20, wt. percent.

Hydrocarbons to be treated should, of course, be reactive with the phosphosulfurizing agent. They include parafiins, olefins, diolefins, acetylenes, aromatics, cyclic aliphatics, and various mixtures of these such as are found in petroleum fractions, condensation products of petroleum fractions, hydrogenated coals, synthetically produced hydrocarbons and the like. Preferred are lubricating oil distillates and base stocks such as bright stock residuums and the like and polyolefins.

The phosphosulfurized hydrocarbons which are utilized as one constituent of the additive combination of the invention are prepared by reacting a C to C olefin polymer with a sulfide of phosphorus. Olefinic polymers prepared by the polymerization or copolymerization of low molecular weight olefins and diolefins such as ethylene, propylene, butylene, isobutylene, butadiene, isoprene, and cyclopentadiene, are suitable materials for the phosphosulfurization. Polymers of monoolefins wherein the molecular weight ranges from about 500 to about 20,000 and preferably ranges from about 600 to about 10,000, e.g. 700 to 2,000 are particularly effective in preparing the phosphosulfurized hydrocarbons of the invention. The most preferred polyolefin employed is a polyisobutylene or polybutene having an average molecular weight of 700 to 1,200, e.g. 940. The average molecular weight of the P 8 treated polyolefin is of some importance in that it has been found that there is a decrease in effectiveness with decreasing molecular weight. For example, P S 100 polybutene of 940 molecular weight is quite effective in reducing the sludge demerit rating in gasoline, while 30 P S 100 polyisobutylene of 660 molecular weight is of reduced effectiveness and 15 P S 100 polyisobutylene of 330 molecular Weight is relatively ineffective. Another preferred hydrocarbon is a bright stock lubricating oil residuum.

One method of carrying out such a polymerization reaction is to employ a Friedel-Crafts catalyst such as boron fluoride or aluminum trichloride at low temperatures in the range of from about 0 F. to about 40 F. Other methods familiar to those skilled in the art, carried out at higher temperatures and with other polymerization catalysts may also be used as described, for example, in US. Patent 2,768,999. 7

The resulting acidic phosphosulfurized hydrocarbon reaction product is then hydrolyzed by steam stripping the product at a temperature of between 100 C. and 200 C., e.g. 140 to 160 C., for a period of time, e.g. l to 6 hours, sufficient to reduce the volatile by-product odor and to bring the acid number to at least 25 and the sulfur content to less than 1.5 wt. percent. This method is more fully described in British Patent 838,928 and British Patent 792,553, hereby introduced by reference.

The hydrolyzed phosphosulfurized polyolefin or bright stock is further stabilized and improved by reacting the acidic hydrolyzed product with a neutralizing agent such that its titratable acidity is at least partially reduced. Neutralizing agents include the alkali and alkaline earth and metal hydroxides, carbonates, and oxides, but preferably include those ashless basic reagents such as ammonia and alkyl and aryl substituted amines and polyamines as previously described. The amount of neutralizing agent employed is usually between 1 to 50% by weight of the acidic product, e.g. 1 to wt. percent, or from 1 to about 10 moles, e.g. 2 to 5 moles, of agent to moles of acidic product, e.g. 2 to 6 moles.

A most preferred class of basic reagents includes organic epoxide compounds such as aryl substituted alkyl epoxides like styrene epoxide; alicyclic epoxides like cyclopentene epoxide; halosubstituted alkylene epoxides such as :chloropropylene oxide; and particularly C to C alkylene oxides such as ethylene oxide, propyleneoxide, butene oxide, and the like. From 1 to 10 moles of these epoxides are reacted with each mole of acidic product as described more fully in British Patent 792,593, hereby incorporated by reference. Although the neutralized product is preferred and the hydrolyzed and neutralized product most preferred, the untreated P 8 polyolefin reaction product itself may be employed, but generally would somewhat reduce the effectiveness.

A further preferred basic reagent to neutralize the acidic product includes the use of from 1 to 10, e.g. 1 to 3, moles per mole of acidic product or sufiicient basic reagent to stoichiometrically neutralize the acidic product of an amide of a carbonic acid or nitrogen or sulfur analogue thereof. Suitable compounds include those having the general formula:

wherein X is oxygen, an imino nitrogen, or a C to C alkyl mono-substituted imino nitrogen, or sulfur, but preferably oxygen; R is a radical selected from the group consisting of hydrogen, alkyl, cycloalkyl, alkenyl, arene, and aryl radicals or combinations thereof with hydrogen and C to (3., alkyl radicals preferred; and R' is a radical selected from the group consisting of ester groups such as OR where R is an alkyl, cycloalkyl, alkenyl arene, and aryl radical, preferably a C to C alkyl radical; and N=(R) and ON(R) wherein R is as defined for R. These basic reagents particularly include, but are not limited to, urea, thiourea, guanidine, the ammonium and amine salts of carbonic acid, e.g. ammonium carbonate, C to C fatty primary amine salts of carbonic acid, urethanes such as ethyl carbamate, butyl carbamate, urylenes, tetraalkyl guanidines like tetramethyl guanidine, quaternary ammonium carbamates such as dimethyl dioleyl carbonates, and the like.

The motor fuels in which the polymeric additives are employed in order to reduce the formation of deposits, sludge and varnish are conventional petroleum distillate fuels boiling in the gasoline boiling point range employed in internal combustion, preferably spark ignition, engines. They are supplied in a number of different grades depending upon the type of service for which they are intended. The copolymers may be employed in all of these grades but are particularly useful in motor and aviation gasolines. Motor gasolines as referred to in connection with the present invention are defined by ASTM Specification D-439-58T in Types A, Band C. They are composed of a mixture of various types of hydrocarbons including aromatics, olefins, paraffins, isoparafiins, naphthenes and, occasionally, diolefins. Those motor fuels containing at least 10% by weight of thermally or catalytically high aromatic components may be especially benefited from the instant invention, Suitable gasolines to which the polymeric additives of the instant invention may be added are those gasolines having an octane number range of 83 to 105 or higher, such as a clear octane number of over 90, for example, over or 100, and comprising over 20% by volume of aromatic hydrocarbons and less than 30% by volume of olefinic hydrocarbons. They are derived from petroleum crude oil by refining processes such as fractional distillation, catalytic cracking, hydroforming, alkylation, isomerization, polymerization and solvent extraction. Motor gasolines normally have boiling ranges between about 70 F. and about 450 F., while aviation gasolines have narrower boiling ranges of between and 330 F. The vapor pressures of gasoline as determined by ASTM Method D-86 vary between about 7 and about 15 p.s.i. at 100 F, The copolymers may also be employed in aviation gasolines which have properties similar to those of motor gasolines, but normally have somewhat higher octane numbers and narrower boiling ranges. The properties of aviation gasolines are set forth in US. Military Specification MIL-F-5572 and ASTM Specification D-910-57T.

The copolymeric additives employed in accordance with the invention may be used in gasolines with other additive agents conventionally used in such fuels. It is common practice to employ from about 0.5 to about 7.0 cc./ gal. of alkyl lead antiknock agents, such as tetraethyl lead, tetrarnethyl lead, dimethyl diethyl lead or a similar alkyl lead antiknock agent or olefinic lead antiknock agents such as tetravinyl lead, triethyl vinyl lead, and the like, or a combination thereof, in both motor gasolines and in aviation gasolines, e.g. 1.0 to 3.0 cc. of tetraethyl lead-tetramethyl lead combination. Antiknock agents may also include other organometallic additives containing lead, iron, nickel, lithium, manganese and the like. Other additives such as those conventionally employed in gasolines may be used such as corrosion inhibitors, antioxidants, antistatic agents, lead octane appreciators like t-butyl acetate, auxiliary scavengers like tri-fi-ehloroethyl phosphate, dyes, anti-icing agents like isopropanol, hexylene glycol and the like.

Catalytically and thermally cracked and reformed gasolines containing a high aromatic content, whether leaded or unleaded, are particularly prone to yield excessive manifold deposits and are improved by addition of the applicants polymeric additives.

Lead antiknock agents are usually employed in conjunction with halogenated hydrocarbon scavenger agents boiling in the range bteween 50 and 250 F., such as ethylene bromide, ethylene chloride, and the like in concentrations of from 0.5 to 3.0 theories, with preferred concentration levels of from 0.8 to 1.5 theories of ethylene bromide used alone or 0.8 to 1.5 of ethylene dichloride and 0.3 to 0.8 of ethylene dibromide when a mixed scavenger is used.

The preparation of the low molecular weight dispersant polymers may be illustrated by the following examples.

EXAMPLE 1 An oil soluble monoalkenyl succinimide is prepared by reacting about 1 mole of a polybutene having an average molecular weight of about 1100 and a carbon chain length of about C with about 1 mole of maleic anhydride at a temperature of about 225 to 250 C. for approximately 6 hours. The resulting product is then dissolved in a 50 wt. percent xylene solution and ethylene diamine gradually added with stirring, maintaining a temperature of about 50 C. during the resulting mod erate exothermic reaction. The water of reaction is azeotropically removed by stripping off the xylene solvent. The resulting polybutene ethylene amine substituted suecinic imide has a nitrogen and oxygen content of approximately 2.4 wt. percent. The use of other diamines in dilferent preparations can vary the percent of nitrogen up to about 6 or even 9 wt. percent to give a different and higher N/O ratio. This oil soluble material will be designated as polymer A.

EXAMPLE 2 A very effective oil soluble additive is prepared by following the teachings of Example 1 except employing a polyisobutylene having an SSU viscosity of between 200 and 10,000 at 210 F., tripropylene diamine, and itaconic .acid as the reactants. This product is designated polymer B.

EXAMPLE 3 An excellent oil soluble dispersant additive is prepared by repeating Example 1 utilizing a polybutene having an average weight of from 1200 to 1600 and employing a tetraethylene pentamine as the polyamine, the resulting product being designated polymer C.

, In the above examples, the dispersant polymer product is generally diluted to a 50 wt. percent solution with a solvent oil or SAE10 mineral oil.

EXAMPLE 4 A low molecular weight, oil soluble, ashless, phosphosulfurized detergent designated polymer E is obtained by treating a polyisobutylene of about 900 average molecular weight with about 15% by weight of P 8 for 8 hours at a temperature of from 180 to 220 C. The resulting acidic product was then blown with steam for about 4 hours at a temperature of to 120 C. to remove the volatile by-product odor and effect hydrogenation. The steam-blown product with about 50 wt. percent diluent oil is then reacted with about 8 wt. percent of ethylene oxide in the presence of a BF ether or sodium hydroxide for about 4 hours at 285 F. The resulting polymer contained about 1.8 wt. percent phosphorus and about 0.9 wt. percent sulfur.

EXAMPLE 5 The above procedure of Example 4 is substantially repeated except that the acidic steam-blown product is treated with about 4.5 wt. percent urea to yield a polymer product designated polymer F and comprising about 1.8 wt. percent phosphorus and 1.1 Wt. percent sulfur and characterized by having an acid number of about 20.

EXAMPLE 6 The above procedure of Example 4 is substantially repeated except that the acidic product is not blown with steam and is reacted with 5% by weight of propylene oxide to yield an oil soluble product designated polymer G.

EXAMPLE 7 A bright stock solvent having a viscosity of about 32 centistokes at 210 F. is treated with about 10% by weight of P 8 at 430 F. for 8 hours. The resulting acidic product is then treated with about 10% by Weight of ethylene oxide at 285 F. for 8 hours to give an oil soluble product designated polymer H comprising about 2.1 wt. percent phosphorus and about 3.6 wt. percent sulfur.

EXAMPLE 8 An ashless, oil soluble, detergent designated polymer I is prepared by treating a polybutene of about 1200 to 1400 molecular weight with about 10% by weight of P S as in Example 4, to produce acidic polybutene phosphosulfurized detergent product.

EXAMPLE 9 The acidic product of Example 8 is hydrolyzed by blowing with steam for at least 6 hours at a temperature of about 100 to C. to produce an oil soluble product having an acid number of at least 50 and with a reduced by-product odor designated polymer K.

EXAMPLE 10 The steam-blown product of Example 9 is substantially neutralized by the addition of a stoichiometric quantity of guanidine to produce a neutralized polymer designated polymer L.

EXAMPLE 11 Example 10 is repeated employing a quaternary ammonium carbamate of trisoya methyl carbamate to yield a product called polymer M.

EXAMPLE 12 To demonstrate the effectiveness of the additive polymeric combination, an engine test employing a motor gasoline having no polymeric additives and having incorporated therein the polymeric additives singly and then in combination was carried out. The gasoline employed had the following general characteristics:

Base gasoline inspections ASTM distillation, method D86:

Initial boiling point, F 91 10% boiling point, F. 127 50% boiling point, F 237 90% boiling point, F. 355 Final boiling point, F. u 428 Reid vapor pressure, p.s.i 11.9 ASTM gum, mg./100 ml 2.6 ASTM breakdown time, min 960+ FIA analysis:

Vol. percent saturates -2. 51.0 Vol. percent olefins 15.7 Vol. percent aromatics a 33.3 Tetraethyl lead, cc./ gal. 2.18 Research octane No. 97 Motor octane No 87 Samples of the base gasoline and samples of the same gasoline containing very small amounts of the polymeric additives singly and in combination were employed in a sustained engine test designed to evaluate gasoline cleanliness performance. A 1950 6-cylinder Chevrolet engine attached to a dynamometer on a test stand was operated on repeated cyclesfor a period of about 110 hours and 220 hours.

At the conclusion of the 110 hour and 220 hour periods, the engine was inspected and various parts were rated in A demerit steps for sludge, deposits and varnish on a demerit scale ranging from to 10, 0 indicating the presence of no deposits at all and signifying that the particular part rated had the maximum amount of deposits it was capable of holding.- The results of these ratings are set forth in the following Table I.

TABLE I.ENGINE CLEANLINESS RESULTS EXAMPLE 14 A clear, highly aromatic, motor gasoline having a Research Octane Number of about 9'5 and containing about by volume of a catalytically hydroformed naphtha and having an ASTM distillation end point of about 425 F. and a Reid vapor pressure of about 9 and to which has been added about 0.004 wt. percent of polymer G and about. 0.02 wt. percent of polymer B enhances the cleanliness ofv the timing gear cover, cylinder head top, and the rocker arm cover of the internal combustion engine operated on said improved fuel.

EXAMPLE 15 A regular gasoline motor fuel having an ASTM 50% distillation point of less than 210 F. is greatly improved in engine cleanliness characteristics after an operating period of more than 110 hours by the addition of about 0.007 wt. percent of polymer H and 0.01 wt. percent of polymer C.

EXAMPLE 16 A spark ignition internal combustion engine operating on the Ott-o cycle and having a compression ratio of between 7/1 and 10/1 has a reduced tendency to form Visual Demerlt Ratings Engine No. 1 2 3 4 No +0.010% Polymer C, +0.015% +0.015% Additive +0.005% Polymer Polymer Polymer F C F Test Time (Hrs) 110 110 220 110 110 Engine Part (Sludge Rating):

Cylinder Head Top 0.50 0 0. 25 0.25 0 Rocker Arm Assembly 0. 50 0 0 0 0. 50 Rocker Arm Cover 0.75 0 0.25 0 0.75 Crankshaft 0. 50 0. 25 0. 25 0 0. 25 Timing Gear Cover. 0. 75 0 0. 25 1. 00 Push Rod Chamber 0.75 0 0 0.25 0.50 Push Rod Chamber Cover 0.75 0 0 0 0.75 Crankcase Bottom l. 00 0. 25 0. 25 0. 25 0. 50 Oil Screen 0.25 0 O 0 0 Overall Average 0. 64 0. 06 0. 11 0. 11 0. 47

The foregoing results demonstrate that the dispersant polymer and the low molecular weight phosphosulfurized detergent polymer in combination gave significantly effective overall engine cleanliness. This combination at extremely low concentration levels produced especially superior engine cleanliness much greater than would be expected from their individual performances.

The data demonstrate that in combination the low molecular weight dispersant and detergent is exceptionally effective in preventing excessive deposits in both 110 and 220 hour tests. The engine cleanliness achieved at the end of the 220 hour test is significant, since dispersant type additives alone tend to become degraded and to give exceptionally poor performance after the initial 110 hour period. That these additives are so effective at such low concentration levels and complement one another to enhance engine cleanliness is an additional demsludge and varnish on upper engine areas not having direct liquid contact with the gasoline by using a gasoline fuel having incorporated therein about 0.006 wt. percent of polymer F and about 0.015 wt. percent of polymer A.

EXAMPLE 17 .hance engine cleanliness.

cracked components and which tend to produce deposits during the operation of internal combustion engines may be upgraded in cleanliness characteristics by incorporation of the following combinations of additives of about 0.010 wt. percent or" dispersant and 0.005 wt. percent of the detergent, e.g., polymers A and F, A and G, B and F, B and L, B and H, A and H, C and M, C-and E, Cand K, and the like.

In addition, these polymers may be injected in concentrate form singly or in combination into the intake manifold, carburetor, fuel lines, or engine combustion chamber in order to promote overall engine cleanliness. Periodic addition of these polymeric additives will en- What is claimed is:

1. An improved motor fuel composition comprising a major amount of a liquid petroleum motor fuel boiling in the gasoline range and a minor amount sufiicient to promote engine cleanliness of an additive combina- 'tion of: (1) dispersant polymer having the general formula wherein R is a C to C polyolefin having an average molecular weight of from 600 to about 3,000, R is selected from the group consisting of hydrogen and C to C alkyl radicals, R is a C to C radical containing substituent groups selected from the group consisting of hydrogen and C to 0., alkyl radicals, R is a C to C alkylene radical, and x is a number from 1 to 6, and (2) a detergent polymer obtained by phosphosulfurizing a C to C polyolefin having a molecular weight between 600 and about 10,000, said polymers being present in a weight ratio of dispersant to detergent of between /1 and 1/5.

2. A fuel composition as defined in claim 1 wherein said R is a polybutene, R is hydrogen, and R" is a methyl group.

3. A fuel composition as defined in claim 1 wherein said detergent polymer is blown with steam at temperatures between 100 and 200 C. until the acid number of the product is at least 25.

4. A fuel composition as defined in claim 1 wherein "said detergent polymer is neutralized with from 1 to 10 moles of a C to C alkylene oxide.

5. A fuel composition as defined in claim 1 wherein said detergent polymer is neutralized with from 1 to 10 moles of an amide having the general formula:

wherein X is selected from the group consisting of oxygen, sulfur, an imino nitrogen, and a C to C alkyl monosubstituted imino nitrogen, and R is a radical selected from the group consisting of hydrogen and C to C alkyl groups.

6. A fuel composition as defined in claim 1 wherein said minor amount is between 0.001 and 1.0 wt. percent.

7. A gasoline to which has been added between 0.001 and 1.0 wt. percent of a combination of (1) a dispersant polymer of N-tetraethylene penta amino m-onoalkenyl succinimide wherein the alkenyl radical is a polybutene having an average molecular weight of between 600 and 3,000 and (2) a detergent polymer obtained by reacting from 5 to 25 wt. percent of P 8 with a polyisobutylene having an average molecular weight of between 700 and 2,000, steam blowing the resulting product at a temperature of from to 200 C. until the acid number of the product is at least 25, and neutralizing the acidic product with a basic reagent selected from the group consisting of urea and ethylene oxide, said'polymers being present in a weight ratio of dispersant to detergent of between 3/1 and 1/1.

8. A gasoline as defined in claim 7 wherein said fuel contains additionally from 0.5 to 3.0 wt. percent of a hydrocarbon solvent having an SUS viscosity of between 50 and 500 at 100 F.

References Cited by the Examiner UNITED STATES PATENTS 2,280,419 4/1942 Wilson 252-33 2,296,069 9/1942 Talbert et a1 4476 2,768,999 10/1956 Hill 25232.7 2,781,319 2/1957 Barnum et al 4462 X 3,018,250 1/1962 Anderson et a1 252--51.5 3,018,291 1/ 1962 Anderson et a1 2525 1.5 3,080,223 3/1963 Monnikendam et a1. 4462 FOREIGN PATENTS 792,553 3/ 1958 Great Britain. 838,928 6/ 1960 Great Britain.

DANIEL E. WYMAN, Primary Examiner. 

1. AN IMPROVED MOTOR FUEL COMPOSITION COMPRISING A MAJOR AMOUNT OF A LIQUID PETROLEUM MOTOR FUEL BOILING IN THE GASOLINE RANGE AND A MONOR AMOUNT SUFFICIENT TO PROMOTE ENGINE CLEANLINESS OF AN ADDITIVE COMBINATION OF: (1) DISPERSANT POLYMER HAVING THE GENERAL FORMULA 